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<td ><a href="../qtdoc/index.html">Qt 5.14</a></td><td ><a href="qtdesigner-manual.html">Qt Designer Manual</a></td><td ><a href="qtdesigner-module.html">C++ Classes</a></td><td >QDesignerCustomWidgetCollectionInterface</td></tr></table><table class="buildversion"><tr>
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<h3><a name="toc">Contents</a></h3>
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<li class="level1"><a href="#public-functions">Public Functions</a></li>
<li class="level1"><a href="#details">Detailed Description</a></li>
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<h1 class="title">QDesignerCustomWidgetCollectionInterface Class</h1>
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<p>The QDesignerCustomWidgetCollectionInterface class allows you to include several custom widgets in one single library. <a href="#details">More...</a></p>
<!-- @@@QDesignerCustomWidgetCollectionInterface -->
<div class="table"><table class="alignedsummary">
<tr><td class="memItemLeft rightAlign topAlign"> Header:</td><td class="memItemRight bottomAlign">   <span class="preprocessor">#include &lt;QDesignerCustomWidgetCollectionInterface&gt;</span>
</td></tr><tr><td class="memItemLeft rightAlign topAlign"> qmake:</td><td class="memItemRight bottomAlign"> QT += designer</td></tr></table></div><ul>
<li><a href="qdesignercustomwidgetcollectioninterface-members.html">List of all members, including inherited members</a></li>
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<a name="public-functions"></a>
<h2 id="public-functions">Public Functions</h2>
<div class="table"><table class="alignedsummary">
<tr><td class="memItemLeft rightAlign topAlign"> virtual </td><td class="memItemRight bottomAlign"><b><a href="qdesignercustomwidgetcollectioninterface.html#dtor.QDesignerCustomWidgetCollectionInterface">~QDesignerCustomWidgetCollectionInterface</a></b>()</td></tr>
<tr><td class="memItemLeft rightAlign topAlign"> virtual QList&lt;QDesignerCustomWidgetInterface *&gt; </td><td class="memItemRight bottomAlign"><b><a href="qdesignercustomwidgetcollectioninterface.html#customWidgets">customWidgets</a></b>() const = 0</td></tr>
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<a name="details"></a>
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<div class="descr">
<h2 id="details">Detailed Description</h2>
<p>When implementing a custom widget plugin, you build it as a separate library. If you want to include several custom widget plugins in the same library, you must in addition subclass QDesignerCustomWidgetCollectionInterface.</p>
<p>QDesignerCustomWidgetCollectionInterface contains one single function returning a list of the collection's <a href="qdesignercustomwidgetinterface.html">QDesignerCustomWidgetInterface</a> objects. For example, if you have several custom widgets <code>CustomWidgetOne</code>, <code>CustomWidgetTwo</code> and <code>CustomWidgetThree</code>, the class definition may look like this:</p>
<pre class="cpp">

  <span class="preprocessor">#include customwidgetoneinterface.h</span>
  <span class="preprocessor">#include customwidgettwointerface.h</span>
  <span class="preprocessor">#include customwidgetthreeinterface.h</span>

  <span class="preprocessor">#include &lt;QtDesigner/qtdesigner.h&gt;</span>
  <span class="preprocessor">#include &lt;QtCore/qplugin.h&gt;</span>

  <span class="keyword">class</span> MyCustomWidgets: <span class="keyword">public</span> <span class="type"><a href="../qtcore/qobject.html">QObject</a></span><span class="operator">,</span> <span class="keyword">public</span> <span class="type"><a href="qdesignercustomwidgetcollectioninterface.html">QDesignerCustomWidgetCollectionInterface</a></span>
  {
      Q_OBJECT
      Q_PLUGIN_METADATA(IID <span class="string">&quot;org.qt-project.Qt.QDesignerCustomWidgetCollectionInterface&quot;</span>)
      Q_INTERFACES(<span class="type"><a href="qdesignercustomwidgetcollectioninterface.html">QDesignerCustomWidgetCollectionInterface</a></span>)

  <span class="keyword">public</span>:
      MyCustomWidgets(<span class="type"><a href="../qtcore/qobject.html">QObject</a></span> <span class="operator">*</span>parent <span class="operator">=</span> <span class="number">0</span>);

      <span class="type"><a href="../qtcore/qlist.html">QList</a></span><span class="operator">&lt;</span><span class="type"><a href="qdesignercustomwidgetinterface.html">QDesignerCustomWidgetInterface</a></span><span class="operator">*</span><span class="operator">&gt;</span> customWidgets() <span class="keyword">const</span> override;

  <span class="keyword">private</span>:
      <span class="type"><a href="../qtcore/qlist.html">QList</a></span><span class="operator">&lt;</span><span class="type"><a href="qdesignercustomwidgetinterface.html">QDesignerCustomWidgetInterface</a></span><span class="operator">*</span><span class="operator">&gt;</span> widgets;
  };

</pre>
<p>In the class constructor you add the interfaces to your custom widgets to the list which you return in the <a href="qdesignercustomwidgetcollectioninterface.html#customWidgets">customWidgets</a>() function:</p>
<pre class="cpp">

  MyCustomWidgets<span class="operator">::</span>MyCustomWidgets(<span class="type"><a href="../qtcore/qobject.html">QObject</a></span> <span class="operator">*</span>parent)
          : <span class="type"><a href="../qtcore/qobject.html">QObject</a></span>(parent)
  {
      widgets<span class="operator">.</span>append(<span class="keyword">new</span> CustomWidgetOneInterface(<span class="keyword">this</span>));
      widgets<span class="operator">.</span>append(<span class="keyword">new</span> CustomWidgetTwoInterface(<span class="keyword">this</span>));
      widgets<span class="operator">.</span>append(<span class="keyword">new</span> CustomWidgetThreeInterface(<span class="keyword">this</span>));
  }

  <span class="type"><a href="../qtcore/qlist.html">QList</a></span><span class="operator">&lt;</span><span class="type"><a href="qdesignercustomwidgetinterface.html">QDesignerCustomWidgetInterface</a></span><span class="operator">*</span><span class="operator">&gt;</span> MyCustomWidgets<span class="operator">::</span>customWidgets() <span class="keyword">const</span>
  {
      <span class="keyword">return</span> widgets;
  }

</pre>
<p>Note that instead of exporting each custom widget plugin using the <a href="../qtcore/qtplugin.html#Q_PLUGIN_METADATA">Q_PLUGIN_METADATA</a>() macro, you export the entire collection. The <a href="../qtcore/qtplugin.html#Q_PLUGIN_METADATA">Q_PLUGIN_METADATA</a>() macro ensures that <i>Qt Designer</i> can access and construct the custom widgets. Without this macro, there is no way for <i>Qt Designer</i> to use them.</p>
</div>
<p><b>See also </b><a href="qdesignercustomwidgetinterface.html">QDesignerCustomWidgetInterface</a> and <a href="designer-creating-custom-widgets.html">Creating Custom Widgets for Qt Designer</a>.</p>
<!-- @@@QDesignerCustomWidgetCollectionInterface -->
<div class="func">
<h2>Member Function Documentation</h2>
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<h3 class="fn" id="dtor.QDesignerCustomWidgetCollectionInterface"><a name="dtor.QDesignerCustomWidgetCollectionInterface"></a><code>[virtual] </code>QDesignerCustomWidgetCollectionInterface::<span class="name">~QDesignerCustomWidgetCollectionInterface</span>()</h3>
<p>Destroys the custom widget collection interface.</p>
<!-- @@@~QDesignerCustomWidgetCollectionInterface -->
<!-- $$$customWidgets[overload1]$$$customWidgets -->
<h3 class="fn" id="customWidgets"><a name="customWidgets"></a><code>[pure virtual] </code><span class="type"><a href="../qtcore/qlist.html">QList</a></span>&lt;<span class="type"><a href="qdesignercustomwidgetinterface.html">QDesignerCustomWidgetInterface</a></span> *&gt; QDesignerCustomWidgetCollectionInterface::<span class="name">customWidgets</span>() const</h3>
<p>Returns a list of interfaces to the collection's custom widgets.</p>
<!-- @@@customWidgets -->
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